Objective To study the detection method of 11a-progesterone and 11a-progesterone acetate by gel permeation chromatography and liquid chromatography, and to provide technical support for market supervision and enterprise quality control. Methods Samples are extracted by ethyl acetate; use 1:1 ethyl acetate: hexane as eluent; purify by gel permeation chromatography (GPC) method; collect the eluent for ${12}\sim {20}\mathrm{\;{min}}$ ; obtain the purified solution from eluent by rotary evaporation; wait for the determination of liquid chromatography. Use 45:55 acetonitrile: water as mobile phase; use C18 $\left({{250}\times {4.6}\mathrm{\;{mm}}}\right)$ chromatographic column for separation; use photo diode array detector for the determination of 11a-progesterone and 11a-progesterone acetate at ${245}\mathrm{\;{nm}}$ . Results The linear correlation coefficient of this method is above 0.995, the recovery rate is ${90.0}\%\sim {102.6}\%$ and 85.1 $\sim {102.7}\%$ , the relative standard deviation (RSD) is ${0.7}\%\sim {2.5}\%$ and ${0.1}\%\sim {8.7}\%$ , the limit of detection is ${0.3}\mathrm{{mg}}/\mathrm{{kg}}$ and 0.6 $\mathrm{{mg}}/\mathrm{{kg}}$ , and the limit of quantification is ${1.0}\mathrm{{mg}}/\mathrm{{kg}}$ and ${2.0}\mathrm{{mg}}/\mathrm{{kg}}$. Conclusion The method is simple, reliable and accurate, and can be used for the determination of 11a-progesterone acetate and 11a-progesterone acetate in cosmetics.